As with all mechanical devices, fuel injectors have physical dimensions that lead to variations between fuel injectors. In addition, each fuel injector has different rates of wear and responds to temperature changes differently. Since the fuel delivered by each fuel injector during a fuel injection event varies enough to affect the performance of an associated engine, it is useful to measure or calculate the fuel delivery by each fuel injector. One challenge with these measurements and calculations is verifying the data is unaffected by non-injection events, such as pumping of fuel and leakage.